diff --git a/src/engine/mod.rs b/src/engine/mod.rs
index 41a637c..92e7aea 100644
--- a/src/engine/mod.rs
+++ b/src/engine/mod.rs
@@ -922,16 +922,20 @@ mod tests {
         // Not identified yet: refused.
         assert!(notice(&to_cs(&mut e, "000AAAAAB", "REGISTER #room"), "must be identified"));
 
-        // Identify, then register.
+        // Identify, then register: sets +r on the channel.
         e.handle(NetEvent::Privmsg { from: "000AAAAAB".into(), to: "42SAAAAAA".into(), text: "IDENTIFY sesame".into() });
-        assert!(notice(&to_cs(&mut e, "000AAAAAB", "REGISTER #room"), "now registered"));
+        let out = to_cs(&mut e, "000AAAAAB", "REGISTER #room");
+        assert!(notice(&out, "now registered"));
+        assert!(out.iter().any(|a| matches!(a, NetAction::ChannelMode { channel, modes } if channel == "#room" && modes == "+r")), "register sets +r: {out:?}");
         assert!(notice(&to_cs(&mut e, "000AAAAAB", "INFO #room"), "alice"));
 
         // A different, unidentified user cannot drop it.
         e.handle(NetEvent::UserConnect { uid: "000AAAAAC".into(), nick: "bob".into() });
         assert!(notice(&to_cs(&mut e, "000AAAAAC", "DROP #room"), "founder"));
 
-        // The founder can.
-        assert!(notice(&to_cs(&mut e, "000AAAAAB", "DROP #room"), "dropped"));
+        // The founder can, which also clears +r.
+        let out = to_cs(&mut e, "000AAAAAB", "DROP #room");
+        assert!(notice(&out, "dropped"));
+        assert!(out.iter().any(|a| matches!(a, NetAction::ChannelMode { channel, modes } if channel == "#room" && modes == "-r")), "drop clears +r: {out:?}");
     }
 }
diff --git a/src/engine/service.rs b/src/engine/service.rs
index 09a57b5..669f52b 100644
--- a/src/engine/service.rs
+++ b/src/engine/service.rs
@@ -74,4 +74,12 @@ impl ServiceCtx {
             nick: nick.to_string(),
         });
     }
+
+    // Set channel modes from services, e.g. "+r" on a registered channel.
+    pub fn channel_mode(&mut self, channel: &str, modes: &str) {
+        self.actions.push(NetAction::ChannelMode {
+            channel: channel.to_string(),
+            modes: modes.to_string(),
+        });
+    }
 }
diff --git a/src/proto/inspircd.rs b/src/proto/inspircd.rs
index ed35884..717390f 100644
--- a/src/proto/inspircd.rs
+++ b/src/proto/inspircd.rs
@@ -179,6 +179,12 @@ impl Protocol for InspIrcd {
                 let now = SystemTime::now().duration_since(UNIX_EPOCH).map(|d| d.as_secs()).unwrap_or(self.ts);
                 vec![self.from_us(format!("SVSNICK {} {} {}", uid, nick, now))]
             }
+            // FMODE <chan> <ts> <modes>. The ircd drops an FMODE whose TS is newer
+            // than the channel's, so we send TS 1 to guarantee it applies to the
+            // existing channel. Sourced from our server, which +r requires.
+            NetAction::ChannelMode { channel, modes } => {
+                vec![self.from_us(format!("FMODE {} 1 {}", channel, modes))]
+            }
             NetAction::Raw(s) => vec![s.clone()],
             // Internal: the link layer handles this before serialization.
             NetAction::DeferRegister { .. } => vec![],
diff --git a/src/proto/mod.rs b/src/proto/mod.rs
index 43271f5..8bee716 100644
--- a/src/proto/mod.rs
+++ b/src/proto/mod.rs
@@ -38,6 +38,9 @@ pub enum NetAction {
     // Force a user's nick (SVSNICK), e.g. renaming to a guest nick on logout.
     // The protocol stamps the new nick's timestamp.
     ForceNick { uid: String, nick: String },
+    // Set channel modes from services, e.g. +r on a registered channel. The
+    // protocol stamps a timestamp the ircd will accept.
+    ChannelMode { channel: String, modes: String },
     Raw(String),
     // Internal only, never serialized to the wire: a registration whose password
     // still needs its (expensive) key derivation. The link layer runs the
diff --git a/src/services/chanserv.rs b/src/services/chanserv.rs
index 365db3e..fc88239 100644
--- a/src/services/chanserv.rs
+++ b/src/services/chanserv.rs
@@ -34,7 +34,10 @@ impl Service for ChanServ {
                     return;
                 };
                 match db.register_channel(chan, account) {
-                    Ok(()) => ctx.notice(me, from.uid, format!("Channel \x02{chan}\x02 is now registered to \x02{account}\x02.")),
+                    Ok(()) => {
+                        ctx.channel_mode(chan, "+r"); // mark the channel registered
+                        ctx.notice(me, from.uid, format!("Channel \x02{chan}\x02 is now registered to \x02{account}\x02."));
+                    }
                     Err(ChanError::Exists) => ctx.notice(me, from.uid, format!("\x02{chan}\x02 is already registered.")),
                     Err(_) => ctx.notice(me, from.uid, "Registration failed, please try again later."),
                 }
@@ -67,7 +70,10 @@ impl Service for ChanServ {
                     return;
                 }
                 match db.drop_channel(chan) {
-                    Ok(()) => ctx.notice(me, from.uid, format!("Channel \x02{chan}\x02 has been dropped.")),
+                    Ok(()) => {
+                        ctx.channel_mode(chan, "-r"); // no longer registered
+                        ctx.notice(me, from.uid, format!("Channel \x02{chan}\x02 has been dropped."));
+                    }
                     Err(_) => ctx.notice(me, from.uid, "Drop failed, please try again later."),
                 }
             }